Return Value

Use the ExecuteScalar method to retrieve a single value (for example, an aggregate value) from a database. This requires less code than using the ExecuteReader method, and then performing the operations necessary to generate the single value using the data returned by an IDataReader.

A typical ExecuteScalar query can be formatted as in the following C# example:

If the first column of the first row in the resultset is not found, a null reference is returned. If the value in the database is a null reference (Nothing in Visual Basic), the query returns DBNull.Value.

The following example creates an instance of the derived class, SqlCommand, and then executes it using ExecuteScalar. The example is passed a string that is a Transact-SQL statement that returns an aggregate result, and a string to use to connect to the data source.